U.S. Pat. No. 3,932,963 issued Jan. 20, 1976 discloses an abrading tool including a body containing a cylinder chamber within which a piston is reciprocable by fluid pressure, and including a shoe adapted to carry a sheet of sandpaper for sanding a work surface. The shoe is reciprocated oppositely from the piston by gear units engaging rack teeth on the piston and the shoe. A flow of air carrying particles abraded from the work surface is drawn by suction through passages in a pad which is carried by the shoe and to which the sandpaper is attached. U.S. Pat. No. 4,145,847 issued Mar. 27, 1979 shows a similar tool having a counterweight which is located near the shoe and is reciprocated oppositely from the shoe and with the piston to reduce the tendency for vibration of the tool body in use. Other similar tools are shown in U.S. Pat. No. 4,052,824 issued Oct. 11, 1977 and U.S. Pat. No. 4,228,620 issued Oct. 21, 1980.